Radioactive method for marking borehole formations



Nov. 13, 1956 s. KRASNOW 2,770,736

RADIOACTIVE METHOD FOR MARKING BOREHOLE FQRMATIONS Original Filed April 10. 1942 TATE.

( [III/11111111111100 IIIIIIIIIIIIIIIII INVENTOR.

United States Fatent O F 1 2,770,736 RADIOACTIVE METHOD FOR MARKING BOREHOLE FORMATIONS Shelley Krasnow, Fairfax County, Va., assignor to Schlumberger Well Surveying Corporation, Houston,

Tex., a corporation of Delaware Original application April 10, 1942, Serial No. 438,475,

now Patent No. 2,592,434, dated April 8, 1952. Di-

vided and this application March 12, 1952, Serial No.

10 Claims. (Cl. 25083.6)

This is a division of my copending application Serial No. 438,475, filed April 10, 1942, for Radioactive Markers, now U. S. Letters Patent No. 2,592,434.

This invention relates to radioactive markers and particularlyto projectiles such as bullets exhibiting radioactive properties, to compositions useful in making or for incorporation into such projectiles, and to methods of utilizing the projectiles and compositions for purposes of marking substances, articles, objects, localities and geological formations for subsequent location, detection, or identification.

The invention will be particularly illustrated by referring to borehole operations without any limitation since it is useful in many directions of which borehole use is exemplary. Such illustration by borehole use is particularly valuable since unique results are secured thereby.

Various objects and advantages of the invention may be referred to in this connection.

In connection with operations carried out in boreholes, it is often desirable to mark formations at a given depth within the borehole so that they may afterward be recognized and located with certainty. This is particularly desirable in view of the fact that such formations may be many thousands of feet underground and any cable or other means utilized to lower an apparatus to that point will necessarily have a variable stretch, and will introduce errors by its use.

Itis desirable to have a marker which may easily be identified and located, and preferably one which can be located through'thicknesses of water, mud, oil, rock and steel casing.- One of the most important uses of such a marker will be in cases where it is desired to mark a formation which has been definitely located by borehole logging or geological means, and which is therefore, of'a certain and-definite nature.

After casing has been driven it is desirable to locate this again so that by its relation to the important strata, other operations may afterwards by conducted.

Other objects and advantages will appear from the more detailed description set forth below, it being undergiven by way. of illustration and explanation only and notiby way' of limitation since various changes therein may be made by those skilled in the art without departing fromthe scope and spirit of the present invention.

In {connection with that more detailed description, reference may be had to the accompanying drawings in which:- i i Figure 1 is a view in longitudinal section of a bullet formed in accordance with the present invention;

Figure 2 is a view in longitudinal section of another form. of bullet;

Figure 3 shows a radioactive pellet; Figure 4 is a view in longitudinal section of an earth core sampling bullet provided with a radioactive insert; Figure 5 is a view in longitudinal section of acore sampling bullet comprising a modification of the fo shown in Figure 4; and Figure 6 is a view in longitudinal section of a core sampling bullet comprising another modification of the form shown in Figure 4.

The present invention is particularly concerned with Patented Nov. 13, 2

the use of projectiles or markers to be positioned in an article, object, stratum, etc., to mark, identify, or locate such article, object, stratum, etc., with an ineradicable mark which is generally unrecognizable except by instruments constructed for use in connection therewith. The projectiles or markers used are desirably those which exhibit ray emission properties, such as radioactivity, and thus lend them properties readily identified by properly sensitive means. A number of illustrations are set forth below.

Referring to Figure 1, a bullet 1 is shown provided with a cavity 2 in which is disposed a radioactive material 12 retained by a plug 3. In Figure 2 a bullet 1' is shown which may be made of a radioactive metal or alloy 32. Thus the metal may itself be radioactive or radioactive material may be dispersed in the metal. The radioactive element is desirably one which either itself gives off rays, or induces rays, such as gamma rays, in other substances.

The radioactive material mentioned above may be a substance which may be artificially activated. Thus oil, sand with oil, which has in turn been subjected to radon gas will be radioactive and serve, or materials artificially activated by nuclear bombardment may be utilized. Thus, a considerable number of the ordinarily non-radioactive elements may be utilized, the particular ones selected being dependent upon the length of time it is desired to have the bullet identifiable by radioactive means. Thus, yttrium will maintain an artificially excited radioactivity for several months, while other substances will maintain such radioactivity for a relatively short time. Sulphur is an example of such a substance. The material 12 of Figure 1 may be of material such as yttrium or sulphur, or the bodies of the projectiles themselves may be of material which will respond readily to artificial activating processes. In appropriate cases, the bullet will be fired, an instrument sent down to activate the bullet, and subsequent radioactive measurements made to determine the exact locality in the manner disclosed in my Patent No. 2,592,434, in which reference is made to the application of Krasnow and Curtiss, Serial No. 137,380, filed April 16, 1937, now abandoned, of. which Patent No. 2,384,840 is a division. Several different types of material'may be utilized for the bullets or the fillings therein in a single borehole, each one marking a separate typeof condition.

By lowering a radioactive source proximate to the bullet, the rays will excite neutrons in the beryllium, which" neutrons will impinge upon the material within the bullet,"

causing artificial temporary radioactivity therein.

Figure 3 shows a pellet 8 madeifin cylindrical form. This may be formed with any of the binders mentioned in the said copendin-g application, Serial No.43 8,475, or may have some simple binder such as starch *or gum arabic. The pellet may be molded in the type of'apparatus com:

monly used by pharmacists for" molding pills or tablets. In cases where it is desired to mark with radioactive material, and not to use a metallic projectile, a pellet suchas shown inFigure 3 may be utilized, made upof explosive material with radioactive substancesintermixedi This may be exploded within the borehole and will spatter the walls of the borehole with radioactive material. This procedure will be useful, for example, where continued erosion or breaking'away is suspected. Successive radio active measurements will indicate whether the material is being eroded, since in such cases theradioactivity will continually diminish more rapidly than would be the case in the absence of erosion.

Figures4-6 illustratethe adaptation of earth core type bullets to the--presentinvention in which sue-h bullets -asordinarily employed in sampling guns, are given radioactive properties.

For example, as shown in Figure 4,

induce neutron emission from the said substance anddetecting "gamma: radiations frorrrthe irradiated mass as in dicative of the neutron emission.

4. In a method of identifying. a particular mass of matethe usual type of such bullet illustrated at 40-may have 5 rial disposed amongthe 'massesmofmaterialthesteps of oneiend thereof internally threaded at 41, and a radioincorporating alocalizedconcentration.ofberylliumin the active collar 42'externally threaded, may be positioned particular.mass subsequently irradiatingthe masses to h h ll S radioactive Collar may be rfldi induce; a neutron emissionfromxther beryllium. and lie active inany. way utilizing any of the expedients set forth tecting radiationsattributable to said neutron emission as above. 1 B.y the use of'a collar 42, having the opening indicative of the presencero f the particular mass. 43, thebullet offers less'resistanceto penetration, 5. In a method ojfddentifyinig a particularmass of mate'- Or; the'wall's of the bullet may be of greater thickness rial disposed among other masses .ofmaterial, ithe steps as Shown 3144 in Figure 5,80 that a recess y' madfi t of incorporating in the particular mass a localized-concenhe cin in o Whichrradioactive material 46 maybe intration of beryllium-anda second substance'capable of c cdfandsuch;recess'th'cn se l d y at 6 Any crnittinggamrna radiations when bombarded with neuradioact ive material 'maybe used as explained above. trons, subsequently irradiating the masses to induce a neuy n Figure r rv bullet ,m y I tron emanation from the ,berylliumjfand detecting the have one-end threaded internally, as at 41; into which presence of gamma radiations as indicative ofthep'r'esehcea plug-48is threaded. Such plug may' be provided with f id particular mass I v t a1rccess49 into wh h radioactive m rial 59 ei h r'in 6 In a'rnethod of operation in a borehole, the steps of loose-0119611 form y he P ahda a 51 t disposing in a formation traversed by'the boreholea-local Positioned t0 hOld the radioactive materiahih p ized concentration of a material which is capable of read it It-is apparent from What has been set forth above, that 11 itti t o when exposed to anirradiating Projectile 0r bullet InEly take any desired form and source,-subsequently passing an irradiating source through may be given radioactive properties in a variety of ways; h b h l t i d ut on emission-from the mate- I11 Specific mention has h made of a rial and detecting radiations throughout the borehole; projectilewhich is driven into the walls of the bore-hole other than f aid soul-Ce to v h f i by explos-ion'or-ot-her driving force. After being driven 7; In a h d f marking borehole, the steps of into thfi WahS 0f borehole, Projectile and its 0011- lodging ina formation traversed by the borehole a markerten-ts remain intact, However, it will be understood that including b lli d a e ond ubstancefcapable of the bulletrnay be constructed so that it will shatter upon emittinggamma di i wh bj t d t 'b mbardcoming Contact with a formatiqn, and will spread mentby neutrons, passingta source of radiations through its contents; Thus, the bullet may havewithi it an the borehole to induce neutronemission from the berylexplosive charge mixed with radioactive material, which 1ium;and detecting thegamma ia i other th sf m Will fixplode When the bullet Comes Cohtact with the the said source-as indicative of the presence of the tnarker.- wallof the-borehole, and will scatter theradioactive n th d f marking formations. i hi o materialzimthe vicinity- In firing, the bullet be hole for-subsequentidentification, the steps of introduc- Omitted entirely and a charge of explosive'and radioactive ing; respectively into at least'two localities correlated with material-t-fired against the wall of theborehole. This. difl ti h i 1 conditions d traversed b t h b a will spatter the wall of the borehole with-the r i 40 hole; localized concentrations of-normally non-radio ctive materials Without ahhlallyl having a Single fi i l materials-capable of;being readily artificially radioacti emhedlitsfilfvated to produce detectably 'different'radiations"when The :methods'. described, while most usefulfor opera Substantially, equally di ed passing c i di i i iz' tl s mayfilsoi-serve to s localities" source "through the borehole; toinduceartificial'radiaunder other Condition Thus, monuments bench tions fr'om the materials,-and performingradioactivm marksnarev oftenplace-d to ,locatexboundary -marks: and me'a'surementsn within, borehole o' b i n Property lines-1 Such monuments Often v covered frorn the respective radiations given off 'by'the artificially ovenwith? vegetation n Sometimes wlmwmd'blown radioactive materialstoidentify the respective localitiesu or drifted earth. Furthermore, for instanceua .pieceof. t; Ima method determining/[he amount t m umbe fiyu m f with an invisible identifying markof the wall of a borehole, the steps of spatterin'g aradioa This piece of lumber may then be identified inuthetfuture t 7 active, material, 0n the walls of a portion of thgborehole the; identifying mark being invisiblesand not detectable-totv ahdnmeasuring, the ,r'adibactivity f thev said, io f, P nsutilizing radioactive measuring-means the borehole at a plurality of different times afterthe I 913ml: 7 a t a i I spattering to obtain data indicative'of the amount-of 1. In amethod of identifying aparticular massof matea f5 erosion of thetborehole' n g t i rial di PQ among-other masses-i the Ste-1750f incorporat' 0 10. .Ini a method off'determi'm'ng the amount oferosiom ing gin the particular mass a localized concentrationofsa V b w n v o b gteps f x i di 1 1 ma non-'radioactivei substance capable? of 3 b i borehole aan explosive material iassociated with radioac-" readily Fl -Yti w i 'subsequehflyiexposlhg -tive material to spatter-the. radioactive material on the the 9f rildlauon tsald walls .of the borehole, and measuring-the radioactivity substance and detectmgradlatlons -1 present-1'11 therboreholesin the vicinity of theexplosionat source andattributable to said activation -ofithesubstance.; aplurafityiof :difierentvtimesuto obtain;datayindicafiye05 l eparticulflri i r the erosion of theborehole'wall; j I t 1 2. In amethod ofident fyingapartlcular massiof mateg V V rial disposed among Other-masses, th P incorr References Cited-'inthe fileof this-Patent 7' 'porating in the particular mass a localized: concentration 7 t a of asubstance capable of readilyemitting neutronswhenr t 'ST IS' S V V V irradiated, subsequently irradiating the total *ndasjses to B n r ---V----.- y 1 excite neutrons in the said substance and detectingIradia-t 7 26,291 Holmblad Apr. 28.; 19,03 ti ons indicative of the presence ofj'the neutron emittingz, 7 7 s'chultlet 2,115 i y 28,4 1903" t an v i v H 70 1,Q54',777"'f Imperiali Mar. 4,1913 t w 3 In a method of identifying a particular masssofr 27 356 s -l -.'---A g-; 3,-

material, thesteps of disposing in theparticularrnass a ,2 8, 'EhniS i s Jan; 14, 9 1 f localized concentration of a substance capable of readily 2,302,247 Neufeld 1 Nov. 17,1942

emitting neutron whenirradiated, subsequently irradiating; 7-5 2,320,643- N f ld --t-- i Jllfle 1943 the-total 'mass, with ;a controlled source'offradiations tor 2,474,581 Howell Q June 28, T249? 7 

10. IN A METHOD OF DETERMINING THE AMOUNT OF EROSION OF THE WALL OF A BOREHOLE, THE STEPS OF EXPLODING IN THE BOREHOLE AN EXPLOSIVE MATERIAL ASSOCIATED WITH RADIOACTIVE MATERIAL TO SPATTER THE RADIOACTIVE MATERIAL ON THE WALLS OF THE BOREHOLE, AND MEASURING THE RADIOACTIVITY PRESENT IN THE BOREHOLE IN THE VICINITY OF THE EXPLOSION AT A PLURALITY OF DIFFERENT TIMES TO OBTAIN DATA INDICATIVE OF THE EROSION OF THE BOREHOLE WALL. 